Hitherto, for a silver halide photographic light-sensitive material, a wet development has been applied using a developing solution after photographing. However, the method has the following inconveniences, and improvement has been desired.
[1] Because development, bleaching, fixing, and drying are carried out, a long time is required for the development processing.
[2] Because plural tanks containing a developing solution are required, a processor cannot be made small in size and light in weight.
[3] Inconveniences, such as the replenishment of a developing solution, the disposal of processing liquids, washing of developing tanks, etc., are required.
For improvement thereof, photographic light-sensitive materials that are processed using a development method by heating (hereinafter, occasionally referred to as "heat development") to a temperature of from 80 to 150.degree. C. are proposed. One example is a method of previously incorporating a precursor for a developing agent in a light-sensitive layer, decomposing the precursor by heating, to form a developing agent, and subjecting to development. In such a heat-development system, the development processing may be carried out by only applying heat, whereby the processing can be carried out in a short time and a processor can be small in size. Furthermore, there are no inconveniences with the replenishment and the disposal of a developing solution.
However, when the light-sensitive material of this system was applied to a printing light-sensitive material, when 4 plates (blue, green, red, and black plates) were piled up, there was a problem that color discrepancy and distortion of an image were caused by the dimensional change that occurred during heat development. In order to solve this problem, there is proposed a method in which use is made of a support having isotropic characteristics and a minimum heat shrinkage, as described in JP-A-3-97523 ("JP-A" as herein used means an unexamined published Japanese patent application). However, the support obtained in accordance with the above-mentioned patent was insufficient for dimensional stability, when subjected to heat development at 80.degree. C. to 150.degree. C. Further, heat fixation is conducted with extension at the time of film formation, in order to decrease in-plane anisotropy accompanied by bowing phenomenon. However, strain (distortion) at the time of film formation was insufficiently relieved by this method, such that the method was unsatisfactory for a photographic support that was required to have high dimensional stability and high flatness within a larger area (0.6 m.times.1 m). Further, this support is subjected to heat treatment with heating while floating the same at 140.degree. C. for 1 to 5 seconds (tension 5 kg/cm.sup.2). However, the dimensional stability on this condition, particularly at a high temperature and short time of 105.degree. C. and 30 minutes, was not only insufficient but also the occurrence of dimples (concavities), due to fluttering or flapping of the support caused by the floating system, was so remarkable that the flatness was insufficient.